The present invention relates generally to the field of computer peripheral devices, and more particularly, is directed to a multimodal touch sensitive peripheral device which greatly enhances the input of information to a computer system.
In most general purpose computer systems, commands and data are entered to the system from a typewriter-style keyboard and information from the system is displayed on a CRT display or printed on a hard copy printing device. Where a CRT is used, the computer normally indicates the current entry position by displaying a distinctive marker called a cursor on the CRT screen. The cursor can take several forms but is usually a flashing underscore or rectangle or a graphical type pointer such as an arrow. The position of the cursor may be controlled in a number of ways. In some systems, a particular keystroke, or combination of keystrokes, is interpreted by the computer as a command to move the cursor to the right, left, up or down. Depending on the system and/or the particular software being used at a time, the cursor may be moved in increments of a single character position, an entire word, line, paragraph or pixel. In many systems, special keys are devoted to these functions and are usually located in a keypad separated from the typewriter keyboard.
Some systems also provide for a pointing device which can be used by the computer to control the location of the cursor on the CRT. Such devices include joysticks, paddles, light pens, touch panels, touch screens, and so-called "mice". All of these devices enable an operator to "point" at a position on the display where the cursor is to be located.
Joysticks and paddles are perhaps the most widely known pointing devices due to their widespread use in video games. These devices are usually of the analog or fixed axis type. The simplest analog joysticks comprise a pair of potentiometers mechanically coupled to a movable handle at right angles to each other. The potentiometers form part of a voltage divider network and as the handle is moved, provide analog signals representing the X and Y coordinate position of the handle. The analog signals may then be converted to digital form for processing by a computer to locate the cursor. The cursor, or other point of interest, can therefore be positioned on the CRT by manipulating the handle. The fixed axis type of joystick is usually comprised of a handle mechanically coupled to a plurality of switches. Each switch represents an axis and direction of movement of the handle. In a 8-axis joystick, 4 switches are provided which indicate handle movement along a vertical, a horizontal and two-diagonal axes. Paddles are similar in operation to joysticks but usually provide a signal indicating movement of the paddle along one axis.
One example of a joystick known in the prior art is disclosed in U.S. Pat. No. 4,313,277 issued in the name of Eder. The Eder joystick provides a pair of 4 bit logic signals which represent the X and Y coordinate axis of the joystick handle. These signals are continuously scanned by an integral microcomputer along with the logic output signals from a small keyboard. The scanned signals are serially transmitted as a modulated infrared light signal to a receiver attached to a computer for demodulation and processing.
Light pens, touch screens and touch panels represent another significant class of pointing devices. Light pen and touch screens are used to detect a desired location on a CRT screen. Light pens usually have a switch in their side or tip which the user activates when the pen is positioned at the desired location on the CRT screen. The light pen then monitors when the pixel under the pen comes on. Based on a reference time signal, the location of the pixel on the CRT screen can then be determined. Touch screens use some form of overlay on the CRT screen which when touched, indicate to the host computer a corresponding location on the screen. Touch panels provide coordinate signals which represent a contact point on the panel. The coordinate signals are usually based on some form of grid scheme.
Mice represent another type of pointing device which have gained popularity with the proliferation of personal computers. Mice sit on a flat surface, such as a table top, and are moved about by hand. In some mouse systems, the movement of wheels or bearings within the mouse are coupled to switches to provide X and Y motion signals. In other systems, the movement of wheels is used to rotate an aperture which interrupts a beam of light to provide the X and Y coordinate signals. U.S. Pat. No. 4,369,439 issued in the name of Broos, U.S. Pat. No. 3,541,541 to Engelbart and U.S. Pat. No. 3,541,521 to Koster disclose mice of the first category while U.S. Pat. No. 4,464,652 issued in the name of Lapson discloses a mouse of the latter category.
Another type of mouse uses a glass grid. A light source inside the mouse is directed toward the grid to determine how many grid lines the mouse crosses as it is moved. This information is then provided to the host computer.
While the above described pointing devices aid in the positioning of the cursor on the CRT screen, they are deficient in a number of areas. For example, analog joysticks are difficult to control, have low resolution and cannot be used to draw straight lines on a CRT screen. Fixed axis joysticks cannot be used to draw complex curves, are slow to move from one place to another and their speed cannot be controlled. Mechanical mice require a large amount of table space to operate, are difficult to maintain in proper orientation, are limited in speed and also cannot be used to draw straight lines. Moreover, mice can readily fall off the operating surface and be damaged and are prone to collection of dirt and dust in their mechanism. Optical mice share many of the same difficiencies as mechanical mice and also require a special operating surface. Light pens require special CRT monitors, are low in accuracy and are fragile in construction. Touch screens obstruct the user's view of the CRT screen and require significant arm motions, and concomitant time delay, for their use. Thus, extended use of touch screens is very fatiguing. Touch screens are also difficult to use due to parallax problems. The above described devices are also deficient in that they all require a significant amount of supervision control and interrogation by the host computer. Thus valuable computer time is used to perform relatively mundane operations. Accordingly, there is a great need in the art for a pointing device which overcomes the above described deficiencies in prior art devices while at the same time being effective, convenient and easy to use. Moreover, different applications require the use of different devices. Thus, there is also a need in the art for a universal or multimodal device to meet the needs and desires of various users and various computer programs.